/*
This file is part of the iText (R) project.
Copyright (c) 1998-2025 Apryse Group NV
Authors: Apryse Software.

This program is offered under a commercial and under the AGPL license.
For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.

AGPL licensing:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
namespace iText.Barcodes.Dmcode {
    /// <summary>This class holds the error correction code for a data block.</summary>
    public sealed class ReedSolomon {
        private static readonly int[] log = new int[] { 0, 255, 1, 240, 2, 225, 241, 53, 3, 38, 226, 133, 242, 43, 
            54, 210, 4, 195, 39, 114, 227, 106, 134, 28, 243, 140, 44, 23, 55, 118, 211, 234, 5, 219, 196, 96, 40, 
            222, 115, 103, 228, 78, 107, 125, 135, 8, 29, 162, 244, 186, 141, 180, 45, 99, 24, 49, 56, 13, 119, 153
            , 212, 199, 235, 91, 6, 76, 220, 217, 197, 11, 97, 184, 41, 36, 223, 253, 116, 138, 104, 193, 229, 86, 
            79, 171, 108, 165, 126, 145, 136, 34, 9, 74, 30, 32, 163, 84, 245, 173, 187, 204, 142, 81, 181, 190, 46
            , 88, 100, 159, 25, 231, 50, 207, 57, 147, 14, 67, 120, 128, 154, 248, 213, 167, 200, 63, 236, 110, 92
            , 176, 7, 161, 77, 124, 221, 102, 218, 95, 198, 90, 12, 152, 98, 48, 185, 179, 42, 209, 37, 132, 224, 
            52, 254, 239, 117, 233, 139, 22, 105, 27, 194, 113, 230, 206, 87, 158, 80, 189, 172, 203, 109, 175, 166
            , 62, 127, 247, 146, 66, 137, 192, 35, 252, 10, 183, 75, 216, 31, 83, 33, 73, 164, 144, 85, 170, 246, 
            65, 174, 61, 188, 202, 205, 157, 143, 169, 82, 72, 182, 215, 191, 251, 47, 178, 89, 151, 101, 94, 160, 
            123, 26, 112, 232, 21, 51, 238, 208, 131, 58, 69, 148, 18, 15, 16, 68, 17, 121, 149, 129, 19, 155, 59, 
            249, 70, 214, 250, 168, 71, 201, 156, 64, 60, 237, 130, 111, 20, 93, 122, 177, 150 };

        private static readonly int[] alog = new int[] { 1, 2, 4, 8, 16, 32, 64, 128, 45, 90, 180, 69, 138, 57, 114
            , 228, 229, 231, 227, 235, 251, 219, 155, 27, 54, 108, 216, 157, 23, 46, 92, 184, 93, 186, 89, 178, 73
            , 146, 9, 18, 36, 72, 144, 13, 26, 52, 104, 208, 141, 55, 110, 220, 149, 7, 14, 28, 56, 112, 224, 237, 
            247, 195, 171, 123, 246, 193, 175, 115, 230, 225, 239, 243, 203, 187, 91, 182, 65, 130, 41, 82, 164, 101
            , 202, 185, 95, 190, 81, 162, 105, 210, 137, 63, 126, 252, 213, 135, 35, 70, 140, 53, 106, 212, 133, 39
            , 78, 156, 21, 42, 84, 168, 125, 250, 217, 159, 19, 38, 76, 152, 29, 58, 116, 232, 253, 215, 131, 43, 
            86, 172, 117, 234, 249, 223, 147, 11, 22, 44, 88, 176, 77, 154, 25, 50, 100, 200, 189, 87, 174, 113, 226
            , 233, 255, 211, 139, 59, 118, 236, 245, 199, 163, 107, 214, 129, 47, 94, 188, 85, 170, 121, 242, 201, 
            191, 83, 166, 97, 194, 169, 127, 254, 209, 143, 51, 102, 204, 181, 71, 142, 49, 98, 196, 165, 103, 206
            , 177, 79, 158, 17, 34, 68, 136, 61, 122, 244, 197, 167, 99, 198, 161, 111, 222, 145, 15, 30, 60, 120, 
            240, 205, 183, 67, 134, 33, 66, 132, 37, 74, 148, 5, 10, 20, 40, 80, 160, 109, 218, 153, 31, 62, 124, 
            248, 221, 151, 3, 6, 12, 24, 48, 96, 192, 173, 119, 238, 241, 207, 179, 75, 150, 1 };

        private static readonly int[] poly5 = new int[] { 228, 48, 15, 111, 62 };

        private static readonly int[] poly7 = new int[] { 23, 68, 144, 134, 240, 92, 254 };

        private static readonly int[] poly10 = new int[] { 28, 24, 185, 166, 223, 248, 116, 255, 110, 61 };

        private static readonly int[] poly11 = new int[] { 175, 138, 205, 12, 194, 168, 39, 245, 60, 97, 120 };

        private static readonly int[] poly12 = new int[] { 41, 153, 158, 91, 61, 42, 142, 213, 97, 178, 100, 242 };

        private static readonly int[] poly14 = new int[] { 156, 97, 192, 252, 95, 9, 157, 119, 138, 45, 18, 186, 83
            , 185 };

        private static readonly int[] poly18 = new int[] { 83, 195, 100, 39, 188, 75, 66, 61, 241, 213, 109, 129, 
            94, 254, 225, 48, 90, 188 };

        private static readonly int[] poly20 = new int[] { 15, 195, 244, 9, 233, 71, 168, 2, 188, 160, 153, 145, 253
            , 79, 108, 82, 27, 174, 186, 172 };

        private static readonly int[] poly24 = new int[] { 52, 190, 88, 205, 109, 39, 176, 21, 155, 197, 251, 223, 
            155, 21, 5, 172, 254, 124, 12, 181, 184, 96, 50, 193 };

        private static readonly int[] poly28 = new int[] { 211, 231, 43, 97, 71, 96, 103, 174, 37, 151, 170, 53, 75
            , 34, 249, 121, 17, 138, 110, 213, 141, 136, 120, 151, 233, 168, 93, 255 };

        private static readonly int[] poly36 = new int[] { 245, 127, 242, 218, 130, 250, 162, 181, 102, 120, 84, 179
            , 220, 251, 80, 182, 229, 18, 2, 4, 68, 33, 101, 137, 95, 119, 115, 44, 175, 184, 59, 25, 225, 98, 81, 
            112 };

        private static readonly int[] poly42 = new int[] { 77, 193, 137, 31, 19, 38, 22, 153, 247, 105, 122, 2, 245
            , 133, 242, 8, 175, 95, 100, 9, 167, 105, 214, 111, 57, 121, 21, 1, 253, 57, 54, 101, 248, 202, 69, 50
            , 150, 177, 226, 5, 9, 5 };

        private static readonly int[] poly48 = new int[] { 245, 132, 172, 223, 96, 32, 117, 22, 238, 133, 238, 231
            , 205, 188, 237, 87, 191, 106, 16, 147, 118, 23, 37, 90, 170, 205, 131, 88, 120, 100, 66, 138, 186, 240
            , 82, 44, 176, 87, 187, 147, 160, 175, 69, 213, 92, 253, 225, 19 };

        private static readonly int[] poly56 = new int[] { 175, 9, 223, 238, 12, 17, 220, 208, 100, 29, 175, 170, 
            230, 192, 215, 235, 150, 159, 36, 223, 38, 200, 132, 54, 228, 146, 218, 234, 117, 203, 29, 232, 144, 238
            , 22, 150, 201, 117, 62, 207, 164, 13, 137, 245, 127, 67, 247, 28, 155, 43, 203, 107, 233, 53, 143, 46
             };

        private static readonly int[] poly62 = new int[] { 242, 93, 169, 50, 144, 210, 39, 118, 202, 188, 201, 189
            , 143, 108, 196, 37, 185, 112, 134, 230, 245, 63, 197, 190, 250, 106, 185, 221, 175, 64, 114, 71, 161, 
            44, 147, 6, 27, 218, 51, 63, 87, 10, 40, 130, 188, 17, 163, 31, 176, 170, 4, 107, 232, 7, 94, 166, 224
            , 124, 86, 47, 11, 204 };

        private static readonly int[] poly68 = new int[] { 220, 228, 173, 89, 251, 149, 159, 56, 89, 33, 147, 244, 
            154, 36, 73, 127, 213, 136, 248, 180, 234, 197, 158, 177, 68, 122, 93, 213, 15, 160, 227, 236, 66, 139
            , 153, 185, 202, 167, 179, 25, 220, 232, 96, 210, 231, 136, 223, 239, 181, 241, 59, 52, 172, 25, 49, 232
            , 211, 189, 64, 54, 108, 153, 132, 63, 96, 103, 82, 186 };

        private static int[] GetPoly(int nc) {
            switch (nc) {
                case 5: {
                    return poly5;
                }

                case 7: {
                    return poly7;
                }

                case 10: {
                    return poly10;
                }

                case 11: {
                    return poly11;
                }

                case 12: {
                    return poly12;
                }

                case 14: {
                    return poly14;
                }

                case 18: {
                    return poly18;
                }

                case 20: {
                    return poly20;
                }

                case 24: {
                    return poly24;
                }

                case 28: {
                    return poly28;
                }

                case 36: {
                    return poly36;
                }

                case 42: {
                    return poly42;
                }

                case 48: {
                    return poly48;
                }

                case 56: {
                    return poly56;
                }

                case 62: {
                    return poly62;
                }

                case 68: {
                    return poly68;
                }
            }
            return null;
        }

        private static void ReedSolomonBlock(byte[] wd, int nd, byte[] ncout, int nc, int[] c) {
            int i;
            int j;
            int k;
            for (i = 0; i <= nc; i++) {
                ncout[i] = 0;
            }
            for (i = 0; i < nd; i++) {
                k = (ncout[0] ^ wd[i]) & 0xff;
                for (j = 0; j < nc; j++) {
                    ncout[j] = (byte)(ncout[j + 1] ^ (k == 0 ? 0 : (byte)alog[(log[k] + log[c[nc - j - 1]]) % 255]));
                }
            }
        }

        /// <summary>Calculates the error correction code for the given parameters.</summary>
        /// <param name="wd">bytearray containing the data</param>
        /// <param name="nd">size of the data</param>
        /// <param name="datablock">size of a datablock</param>
        /// <param name="nc">size of a errorblock</param>
        public static void GenerateECC(byte[] wd, int nd, int datablock, int nc) {
            int blocks = (nd + 2) / datablock;
            int b;
            byte[] buf = new byte[256];
            byte[] ecc = new byte[256];
            int[] c = GetPoly(nc);
            for (b = 0; b < blocks; b++) {
                int n;
                int p = 0;
                for (n = b; n < nd; n += blocks) {
                    buf[p++] = wd[n];
                }
                ReedSolomonBlock(buf, p, ecc, nc, c);
                p = 0;
                for (n = b; n < nc * blocks; n += blocks) {
                    wd[nd + n] = ecc[p++];
                }
            }
        }
    }
}
